Plastic Moulded Part and Method for the Production Thereof

ABSTRACT

The invention relates to a method for producing a plastic molded part ( 1 ), comprising the steps of:
     a) providing a first decorative film ( 11 ), which at least partially has an opaque coating ( 112 );   b) introducing at least one decorative element of a decoration into the first decorative film ( 11 ) by machining using a machining tool;   c) providing a second decorative film ( 12 );   d) placing the decorative films ( 11, 12 ) into an injection mold ( 2 ) having a first ( 21 ) and second mold half ( 22 ), which together form a cavity ( 23 ) for molding the plastic molded part ( 1 ), the first decorative film ( 11 ) being placed on a first wall ( 22   f ) of the cavity ( 23 ) and the second decorative film ( 12 ) on a second wall ( 21   f ) of the cavity ( 23 ) lying opposite the first wall ( 22   f );   e) back-injecting the decorative films ( 11, 12 ) with a polymer melt, so that the first decorative film ( 11 ) forms a first surface and the second decorative film ( 12 ) forms a second surface of the plastic molded part ( 1 ) opposite the first surface.

The invention relates to a plastic molded part and to a method for theproduction thereof.

In order to create plastic molded parts with decorative surfaces, it isknown to place decorative films into injection molds and to back-injectthem with a polymer melt.

The surfaces of these molded parts are subject to high demands. Inparticular, they have to be resistant to substances with which they comeinto contact in daily use, such as for example fingerprints, nailvarnish remover and the like, as well as having to resist mechanicalloads as far as possible without scratching. The surfaces of thesemolded parts are also subject to high optical demands, and therefore thesurface should have an optically high-quality and/or attractiveappearance.

In order to achieve good resistance of the surfaces and/or a desiredoptical appearance of the surface, it is conventional to apply at leastone protective lacquer coat on to the molded parts by means of wetcoating after the polymer melt has cured. By means of this wet coating,further decorative elements can also be applied at the same time.

However, a coating step of this type makes the manufacture of theplastic molded part significantly more complex and cost-intensive. Atthe same time, it is not always possible to achieve the desiredtolerances in positioning the decorative elements using this step.

The object of the present invention is to provide a plastic molded partand a method for the production thereof.

This object is achieved by a method having the features of claim 1 andby a plastic molded part having the features of claim 26.

Such a method for producing a plastic molded part comprises the stepsof:

-   -   a) providing a first decorative film, which is at least        partially provided with an opaque coating;    -   b) introducing at least one decorative element of a decoration        into the first decorative film by machining using a machining        tool;    -   c) providing a second decorative film;    -   d) placing the decorative films into an injection mold having a        first and second mold half, which together form a cavity for        molding the plastic molded part, the first decorative film being        placed on a first wall of the cavity and the second decorative        film on a second wall of the cavity lying opposite the first        wall;    -   e) back-injecting the decorative films with a polymer melt, so        that the first decorative film forms a first surface and the        second decorative film forms a second surface of the plastic        molded part opposite the first surface.

Using a method of this type, a plastic molded part can be obtained, saidpart comprising a first decorative film, which at least partially has anopaque coating, into which a decoration is introduced, and comprising asecond decorative film, the first decorative film forming a firstsurface and the second decorative film forming a second surface of theplastic molded part opposite the first surface.

In step b), the introduction of the at least one decorative element of adecoration into the first decorative film can take place in particularby laser irradiation and/or by milling and/or stamping. The machiningtool is therefore preferably a laser, a milling tool and/or a stampingtool.

The two decorative films preferably form a protection for both surfacesof the plastic molded part, so that this is particularly resistant. Awet coating of the plastic molded part after the polymer melt has curedcan therefore be omitted, and so the finished part is obtained directly.In the assembled state of the plastic molded part, the first decorativefilm preferably forms the back thereof, and so the optical quality ofthe opaque layer does not have to be excessively high. The importantthing is only that the decoration introduced in particular by laserirradiation, milling or stamping, which is preferably subsequentlybacklit, is of high quality.

At the same time, through the combination of the two decorative films, aparticularly high design freedom and precision is obtained. The twofilms preferably have decorative elements or design elements thatsupplement one another, e.g. complementary patterns, which for examplesupplement one another to form an overall design or an overalldecoration when observed and/or backlit, and/or give an opticallyvariable effect when observed from different angles.

The tolerances that can be achieved in introducing the design are in therange of +/−0.1 mm, whereas with alternative methods, for example theuse of pre-stamped transfer films, tolerances of only +/−0.2 mm can beachieved for small parts and of only +/−1 mm for larger parts.

Furthermore, laser irradiation, milling or stamping is not bound tofixed designs. Thus, it is possible, for example, to manufactureindividualized designs or highly flexible small series without anyadditional expense. The laser or milling head is electronicallycontrolled here, with control signals controlling the position of thelaser beam, milling head or stamping blade on the surface of the moldedpart. The control signals can be modified specifically to the parts,i.e. for each individual molded part or for a specific number of moldedparts.

A stamping blade or punch is advantageous in particular when it isdesired to introduce relatively large-area decorations or decorativeelements and this introduction would take too long using a finelystructuring tool such as a laser beam or milling head. The use of astamping blade or punch is likewise expedient if the decoration or thedecorative elements have repeating motifs of the same type, e.g.circles, dots, stars, symbols or letters.

Preferably, the decoration and/or the at least one decorative element isintroduced into the first decorative film by laser irradiation, millingor stamping after the back injection. This makes it possible to place orposition the decoration and/or the at least one decorative elementparticularly accurately, because important operational steps thatdisturb or negatively affect the placing and/or positioning of thedecoration and/or of the at least one decorative element (in particularthe positioning of the decorative films in the injection mold and theback injection) have already taken place.

Alternatively, however, it is also possible for the decoration and/orthe at least one decorative element to be introduced into the firstdecorative film by laser irradiation, milling or stamping before theback injection and in particular before the first decorative film isplaced into the injection mold.

Preferably, when the decoration and/or the at least one decorativeelement is introduced into the first decorative film by laserirradiation, milling or stamping, the opaque coating is at leastpartially removed in the area machined with the machining tool and/orthe opacity of the opaque coating is reduced in the area machined withthe machining tool.

The opaque coating can be accurately ablated by laser irradiation,milling or stamping so that symbols or other decorative elements to bebacklit can be introduced in this way. Where the material of the opaquecoating is hit by the laser beam here, it is heated and evaporated and,as a result, removed. In the case of milling or stamping, the materialof the opaque coating is removed mechanically.

Suitable for this purpose are materials such as opaque colored-lacquercoats with high pigmentation, for example carbon black pigments, forexample composed of pigments in a polymeric, generally transparentbinder, the proportion and nature of the pigments determining theopacity of the lacquer, metal layers of aluminum, chromium or copper orthe like. A metal layer of vapor-deposition-coated and cluster-formingtin as a non-conductive metal layer (so-called NCVM coats(NCVM=Non-Conductive Vacuum Metallization)) is likewise possible.Materials that change their optical properties during laser irradiation,in particular their opacity or transparency, can also be used as amaterial for the opaque coating.

For the laser irradiation an Nd:YAG laser is preferably employed, whichin particular emits light in the infrared range. The necessary intensityof the laser beam depends on the nature and thickness of the opaquecoating as well as on the rate at which the opaque coating is to beremoved.

It has proved useful if the pigmentation of the colored lacquer layer isselected such that a pigment index PI is in the range of 1.5 cm³/g to120 cm³/g, in particular in the range of 5 cm³/g to 120 cm³/g, thepigment index PI being calculated according to:

${PI} = {\sum\limits_{1}^{x}\; \frac{\left( {m_{P} \times f} \right)_{x}}{\left( {m_{B} + m_{A}} \right)}}$and ${f = \frac{OA}{d}},$

wherein the following applies:m_(P)=mass of a pigment in the colored lacquer layer in g,m_(B)=constant; mass of a binder in the colored lacquer layer in g,m_(A)=constant; mass of solids in the additives in the colored lacquerlayer in g,OA=oil absorption value of a pigment (according to DIN 53199),d=density of a pigment (according to DIN 53193),x=control variable, corresponding to the number of different pigments inthe colored lacquer layer.

In this way, starting from a composition of a colored lacquer layer thathas been found to be suitable, other possible pigmentations differingfrom this can be calculated rapidly in an uncomplicated manner.

It has proved advantageous if a pigmentation of the colored lacquerlayer is selected such that a transmission T of visible light throughthe opaque coating is less than 50%. The transmission T, i.e. thetransmittance of the opaque coating, is determined in particular with aspectrophotometer, for example of the Hitachi U-2000 type, measurementspreferably being taken in a wavelength range of between 360 nm and 700nm.

After the decoration and/or the at least one decorative element has beenintroduced into the first decorative film, the area machined with themachining tool and the area not machined with the machining toolpreferably have a difference in transparency such that it is perceptibleby a human observer without any aids when viewed with transmitted light.The difference in transparency here is in particular at least 5% andpreferably at least 10% to 75%. This ensures that adequate contrast ispresent in the decoration, so that a sharply defined and readilyperceptible decoration is obtained.

The opaque coating is applied preferably by printing, in particularscreen printing or intaglio printing. The printing in this case can takeplace over the entire surface or part of the surface. It is alsopossible to perform multiple printing operations in succession in orderto achieve the desired degree of coverage or the desired opacity. Inthis case, additional layers, such as, for example, colored transparentor translucent layers, protective lacquers or the like, can also beprinted on at the same time over the entire surface or part of thesurface.

Alternatively, the opaque coating can be applied using a transfer film.Here too, application can take place over the entire surface or part ofthe surface. A transfer film of this type typically comprises a carrierlayer, an optional release layer and, as the transfer ply, one or moredecorative layers, which can provide different degrees of coverage,and/or an adhesive layer. The carrier layer is removed after theapplication of the transfer film, the transfer ply remaining on thedecorative film with the other layers. The opaque coating is then formedby at least one of the decorative layers and consists of the materialsalready mentioned.

Before the decoration is introduced, the opaque coating preferably has atransparency in the wavelength range visible to humans of less than 50%,in particular of less than 20%, preferably less than 5%. This provides abackground of dark appearance, which offers a good contrast forsubsequent backlighting.

It is also expedient if, after the decoration has been introduced, theopaque coating has a transparency in the wavelength range visible tohumans of more than 50%, in particular of more than 75%, in the areamachined with the machining tool. This allows a readily perceptiblebacklighting effect to be obtained. The transparency can also vary atdifferent wavelengths visible to humans, so that colored backlighting isobtained.

The opaque coating preferably has a layer thickness of less than 100 μm,in particular in a layer thickness of between 5 μm and 50 μm. Thisensures on the one hand the necessary opacity and on the other hand theproduction of a thin and optionally flexible plastic molded part.

It is furthermore preferred if the first decorative film has at leastone further at least partial coating, in particular a transparent ortranslucent colored coating, a protective lacquer coating and/or anadhesive coating. These coatings can be applied by printing or using atransfer film as explained above. Combinations of these techniques arealso possible. As a result, additional visual effects can be achieved oradditional functions integrated into the decorative film.

The decoration and/or the at least one decorative element preferably isor comprises a logo, a symbol and/or at least one alphanumericcharacter. These elements can also be combined with abstract graphicdesign elements as decorative elements. The decoration can possess apurely ornamental function, but can preferably also be functional and,for example, denote display or control elements of a device, such asstatus displays, control surfaces or the like.

Preferably, at least one further decorative element is introduced intothe first decorative film by stamping. This allows large-area recessesto be provided for display elements, for backlighting or the like,without the need for a lengthy laser treatment or milling treatment ofthese areas.

It is further preferred if the first decorative film is deep-drawnbefore being placed into the injection mold. This enables so-calledinserts to be produced, which can in particular be shapedthree-dimensionally before back injection to a greater extent than isoften possible during back injection.

Conventional deep-drawing methods can be used here. In general, thefirst decorative film is provided as sheet stock and placed into adeep-drawing mold, which has the desired finished contours. By applyingheat, preferably a temperature of 80° C. to 200° C., the decorative filmis rendered deformable. The film can now be adapted to the shape of thedeep-drawing mold and thus brought into the desired finished contours byapplying a vacuum and/or by applying a forming die and/or positive airpressure. Upon cooling, the material of the first decorative film thenhardens again, so that said film retains the finished contours.

After deep-drawing, mechanical finishing can optionally also take place,for example by cutting (mechanically or using a laser), milling,stamping or the like.

The first decorative film in this case preferably has a thickness of 50μm to 2000 μm. This on the one hand ensures good mechanical stabilityand on the other hand allows problem-free shaping.

The first decorative film preferably has at least one ply composed of acolorless or colored transparent or translucent thermoplastic material,in particular of ABS, ABS/PC, PC/ABS, PC, PP or PMMA. This serves as acarrier for the opaque coating and any further layers that may bepresent, but can itself be backlit. Because of the thermoplastic natureof the named materials, problem-free forming is possible.

It is further preferred if the at least one decorative element and/ordecoration that has been introduced comprises at least one line having aline thickness of at least 50 μm, in particular of at least 0.5 mm.These lines can be part of the above-mentioned decorative elements orcan form these, i.e. for example letters, symbols or logos. The minimumline thickness is determined by the resolving power and perceptiveability of the eye. Because of the backlighting, even extremely finelines are still perceptible. The maximum line thickness or maximumextent of the decorative elements is limited only by the nature of thedecorative elements.

It is also expedient if the second decorative film comprises a carrierlayer, an optional release layer and at least one decorative ply thatcan be detached therefrom and that the carrier layer is removed from thedecorative ply after the back injection. It is therefore a transferfilm, as has already been described with reference to the application ofthe opaque coating on to the first decorative film. The carrier layercan also remain on the plastic molded part until the plastic molded partis installed, thus providing additional protection of the surface duringhandling.

Alternatively, the second decorative film can be formed in a similarmanner to the first decorative film. To this end, the second decorativefilm preferably has at least one ply composed of a colorless or coloredtransparent or translucent thermoplastic material, in particular of ABS,ABS/PC, PC/ABS, PC, PP or PMMA. This serves as a carrier for thedecorative ply of the second decorative film.

In this alternative embodiment of the second decorative film, as for thefirst decorative film, it is advantageous if the second decorative filmis deep-drawn before being placed into the injection mold. This enablesso-called inserts to be produced, which can in particular be shapedthree-dimensionally before back injection to a greater extent than isoften possible during back injection.

Conventional deep-drawing methods can be used here. In general, thesecond decorative film is provided as sheet stock and placed into adeep-drawing mold, which has the desired finished contours. By applyingheat, preferably a temperature of 80° C. to 200° C., the decorative filmis rendered deformable. The film can now be adapted to the shape of thedeep-drawing mold and thus brought into the desired finished contours byapplying a vacuum and/or by applying a forming die and/or positive airpressure. Upon cooling, the material of the second decorative film thenhardens again, so that said film retains the finished contours.

The decorative ply of the second decorative film preferably comprises atleast one protective lacquer coat which is high-gloss or matt and/or hasbeen provided with a tactile structure. The protective lacquer coat herecan be colorless or colored translucent or transparent or can also haveopaque areas. In particular, it is preferred if the decorative ply formsa further decoration, which interacts with the at least one decorativeelement and/or decoration of the first decorative film.

Preferably, in order to form the tactile structure during backinjection, in particular a tactile surface relief is molded into thesurface of the second decorative film facing away from the polymer melt,in particular based on a pattern layer, which is disposed between thewall of the cavity and a carrier film of the second decorative film orthe second decorative film.

The tactile structure is thus formed during injection molding, when thesecond decorative film is capable of plastic deformation because of theheat and pressure of the injected polymer melt. The pattern layer can beformed directly by the wall of the cavity or can preferably be providedby a separate insert, in particular by the carrier film itself.

The second decorative film is preferably transparent or translucent atleast in some areas and in particular has a transparency of 5% to 100%.In this way, the backlit at least one decorative element and/ordecoration of the first decorative film can also be readily perceivedfrom the side of the second decorative film.

It is preferred if the decorative films are placed into the injectionmold with a spacing of 0.5 mm to 10 mm, preferably of 0.8 mm to 5 mm.This spacing determines the wall thickness of the finished plasticmolded part.

It is further preferred if at least one core is introduced into theinjection mold between the decorative films. This enables hollows orrecesses to be introduced into the plastic molded part, which can beused to hold functional elements, for example separate components suchas displays, switches, controls or separate backlighting devices and/ortouch sensors or the like. The core is preferably introduced into thespace between the decorative films through a cut-out in the firstdecorative film.

Furthermore, it is possible that after the back injection, at least onefunctional element, in particular a backlighting device and/or a touchsensor, is applied, in particular bonded or laminated, on the side ofthe plastic molded part formed by the first decorative film. Thefunctional element can additionally or alternatively comprise electricalwires and/or electrical/electronic components.

The first and/or second decorative film itself can preferably alsocomprise one or more electrical functional layers, comprising inparticular a backlighting device or one or more touch sensors, inparticular capacitive touch sensors.

Various functional elements can be integrated into the plastic moldedpart by any of the methods described, so that said part can be used as acontrol device, display element or the like.

Furthermore, the injection-molding compound is preferably transparent ortranslucent, in particular with a transparency of 5% to 98%, preferablycomposed of one of the following materials: ABS(acrylonitrile-butadiene-styrene copolymer), PC (polycarbonate), ABS/PC,PC/ABS, PMMA (polymethyl methacrylate), PP (polypropylene), PA(polyamide) and TPU (thermoplastic polyurethane).

This can ensure good backlighting of the plastic molded part. To processthe named materials, injection molding at preferred temperatures of 200°C. to 300° C. is suitable. The necessary injection pressure depends inparticular on part size, part geometry and wall thickness and can varywithin a wide range.

In particular by varying the transparency of the second decorative filmand/or the injection-molding compound and/or the contrast (difference intransparency) in the first decorative film, very different opticaleffects can be created.

For example, the contrast in the first decorative film can be adjustedto be very high by a highly transparent first carrier film and completeremoval of the very low-transparency opaque coating. When a likewisehighly transparent injection-molding compound is used, the visibility ofthe decorative elements can be controlled with the aid of thetransparency of the second decorative film. If the second decorativefilm is likewise highly transparent, there is very clear visibility ofthe decorative elements because the contrast established in the firstdecorative film is also still readily visible through the seconddecorative film. If the second decorative film is less transparent, thevisibility of the decorative elements can be reduced and at the sametime an impression of very high opacity of the second decorative filmcan be created in the non-backlit state. Only in the backlit state canit then be perceived that the second decorative film is not actuallyopaque but translucent or transparent.

However, it is also possible to reduce the transparency and/or contrastof the first decorative film and its decorative elements and/or of theinjection-molding compound. The transparency of the second decorativefilm then only partially determines how strongly or clearly thedecorative elements can be seen through it.

Exemplary embodiments of such a plastic molded part and methods for theproduction thereof are explained in more detail below with reference tothe drawing. There are shown in:

FIG. 1 A schematic sectional illustration through an exemplaryembodiment of a plastic molded part with a decorative film on the frontand on the back;

FIG. 2 A schematic view of a decorative film for a plastic molded partaccording to FIG. 1;

FIG. 3 A schematic sectional view through an injection molding tool inthe opened state;

FIG. 4 A schematic sectional view through the injection molding toolaccording to FIG. 3 in the closed state;

FIG. 5 A schematic illustration of various design variants of a plasticmolded part.

A plastic molded part 1, in particular for a control surface or displaysurface of a device, comprises a first decorative film 11, a seconddecorative film 12 and a base element 13, wherein the decorative films11 and 12 are disposed on opposite sides of the base element 13. In asubsequent installed position of the plastic molded part 1, the firstdecorative film 11 forms the back thereof and the second decorative film12 the front thereof, facing a user.

The first decorative film 11 has a multilayer construction and comprisesat least one carrier ply 111 and an opaque coating 112. The carrier ply111 preferably has a layer thickness of 50 μm to 2000 μm, in particularof 100 μm to 1000 μm, and consists of a transparent or translucentthermoplastic polymer, in particular of ABS, ABS/PC, PC/ABS, PC, PP orPMMA, PA or TPU.

The opaque coating 122 consists of an opaque lacquer, for example one ormore opaque colored lacquer layers having a high content of pigments,for example carbon black pigments, and/or of a metal such as aluminum orcopper or the like. The opaque coating 122 can preferably be applied byprinting, in particular screen printing or intaglio printing. Theprinting in this case can take place over the entire surface or part ofthe surface. It is also possible to perform multiple printing operationsin succession in order to achieve the desired degree of coverage or thedesired opacity. In this case, additional layers 113, such as forexample colored transparent or translucent layers, protective lacquersor the like, can also be printed on at the same time over the entiresurface or part of the surface.

Alternatively, the opaque coating 112 can be applied using a transferfilm. Here too, application can take place over the entire surface orpart of the surface. A transfer film of this type typically comprises acarrier layer, an optional release layer and a transfer ply detachabletherefrom having one or more decorative layers 113, which can providedifferent degrees of coverage, and/or an adhesive layer. The carrierlayer is removed after the transfer ply has been applied on to thedecorative film 11, the other layers 112, 113 remaining on thedecorative film 11.

By laser irradiation, milling or stamping, the opaque coating 112 can beremoved accurately from the decorative film 11, so that symbols or otherdecorative elements to be backlit can be introduced in this way. Anexample of such a decoration is shown in FIG. 2. Here, the material ofthe opaque coating 112 is heated and evaporated in the areas 112 a whereit is hit by the laser beam and is thereby removed. In the case ofmilling or stamping, the material of the opaque coating 112 is removedmechanically in the areas 112 a.

It is also possible to use materials that change their opticalproperties, in particular their opacity or transparency, during laserirradiation, for example special bleachable pigments or pigments thatdisplay a color change by means of suitable laser irradiation.

For the laser irradiation an Nd:YAG laser is preferably employed, whichin particular emits light in the infrared range. The necessary intensityof the laser beam depends on the nature and thickness of the opaquecoating as well as on the rate at which the opaque coating is to beremoved.

The areas 112 a machined with the machining tool preferably form lineshaving a line thickness of at least 50 μm, in particular of at least 0.5mm, which form decorative elements such as letters, numbers, symbols orlogos. The minimum line thickness is determined by the resolving powerand perceptive ability of the eye. As a result of the backlighting, evenextremely fine lines are still perceptible. The maximum line thicknessor maximum extent of the decorative elements is limited only by thenature of the decorative elements.

After the decoration has been introduced into the first decorative film11, the areas 112 a machined with the machining tool and the areas 112 bnot machined with the machining tool preferably have a difference intransparency of at least 10%, preferably of 20% to 75%. This ensuresthat adequate contrast is present in the decoration so that a sharplydefined and readily perceptible decoration is obtained.

Before the introduction of the, the opaque coating 112 preferably has atransparency in the wavelength range visible to humans preferably ofless than 50%, in particular of less than 20%, preferably less than 5%.This provides a background of dark appearance, which offers a goodcontrast for subsequent backlighting.

After the decoration has been introduced, the opaque coating 112 has atransparency in the wavelength range visible to humans of more than 50%,in particular of more than 75%, in the area 112 a machined with themachining tool. This allows a readily perceptible backlighting effect tobe obtained. The transparency can also vary at different wavelengthsvisible to humans, so that colored backlighting is obtained.

The opaque coating 112 preferably has a layer thickness of less than 100μm, in particular in a layer thickness of between 5 μm and 50 μm. Thisensures on the one hand the necessary opacity and on the other hand theproduction of a thin and optionally flexible plastic molded part.Overall, the first decorative film 11 preferably has a layer thicknessof 50 μm to 2000 μm.

On the back of the first decorative film 11, further functional elements114 can also be applied. These can be in particular a backlightingdevice or one or more touch sensors, in particular capacitive touchsensors. The decorative film 11 itself can also comprise one or moreelectrical functional layers comprising in particular a backlightingdevice or one or more touch sensors, in particular capacitive touchsensors.

The second decorative film 12 in the embodiment as a transfer filmcomprises a carrier layer 121, an optional release layer and at leastone decorative ply 122, 123. The carrier layer 121 is removed from thedecorative ply 122, 123 after the application of the second decorativefilm 12. Carrier layer 121 and release layer are therefore no longerpresent in the finished component. However, the carrier layer 121 canalso, as shown in FIG. 1, remain on the plastic molded part 1 until theplastic molded part 1 is installed, thus providing additional protectionof the surface during handling.

The carrier layer 121 preferably consists of PET (polyethyleneterephthalate) or PMMA or PC and has a layer thickness of 6 μm to 50 μm.

In the alternative embodiment as in particular a deep-drawn insert, thecarrier layer 121 of the second decorative film 12 has a layer thicknesspreferably of 50 μm to 2000 μm, in particular of 100 μm to 1000 μm, andconsists of a transparent or translucent thermoplastic polymer, inparticular of ABS, ABS/PC, PC/ABS, PC, PP or PMMA, PA or TPU. Thecarrier layer 121 in this case has no release layer and serves as acarrier for the decorative ply 122, 123.

The at least one decorative ply 122, 123 comprises at least oneprotective lacquer coat 122 which is high-gloss or matt and/or has beenprovided with a tactile structure, for example a brushed surface. Thesurface effects in this case can also be partially present or can formadjacent surfaces. The protective lacquer coat 122 can be colorless orcolored translucent or transparent or can have opaque areas.

The protective lacquer of the protective lacquer coat 122 here ispreferably a radiation-cured lacquer, such as for example a physicallydrying binder system based on polyacrylic and PU resins, which can becured to completion after the plastic molded part 1 is completed. Thistakes place preferably by irradiation at a wavelength of 200 nm to 400nm.

The second decorative film 12 is preferably transparent or translucentat least in some areas and in particular has a transparency of 20% to100%. In this way, the backlit at least one decorative element and/ordecoration of the first decorative film 11 can also be readily perceivedfrom the side of the second decorative film 12.

Overall, the layer thickness of the second decorative film 12 in theembodiment as a transfer film is preferably approximately 10 μm to 100μm, with the decorative plies 122, 123 preferably each having a layerthickness of 1 μm to 50 μm. In the embodiment as an insert, the totallayer thickness of the second decorative film 12 is preferablyapproximately 50 μm to 2000 μm, with the decorative plies 122, 123 eachhaving a layer thickness of 1 μm to 50 μm.

Furthermore, the decorative ply 122, 123 can form a further decoration,which interacts with the decoration of the first decorative film 11. Forexample, the two decorative films 11, 12 can each exhibit patternswhich, when superimposed, display the desired final decoration. It isalso possible to utilize the spacing between the decorative films 11,12, for example to create an optically variable design by means ofparallax effects.

The base element 13 is preferably made of a transparent or translucentthermoplastic polymer, preferably acrylonitrile-butadiene-styrenecopolymer (ABS), polycarbonate (PC), polypropylene (PP), polymethylmethacrylate (PMMA) or a mixture of polycarbonate andacrylonitrile-butadiene-styrene copolymer (PC/ABS).

The transparency of the base element 13 is preferably from 5% to 98%.The layer thickness of the base element 13 is preferably 0.5 mm to 10mm, preferably from 0.8 mm to 5 mm. Furthermore, hollows or recesses canalso be introduced into the base element 13, into which furtherfunctional elements, such as displays or sensors, can be integrated.

The production of the plastic molded part 1 takes place by injectionmolding. FIG. 3 shows a schematic sectional illustration of aninjection-molding device 2 having a first mold half 21 and a second moldhalf 22. The first mold half 21 is designed to be movable relative tothe fixed second mold half 22. The two mold halves have molding surfaces21 f and 22 f, which form a cavity 23.

In the exemplary embodiment illustrated in FIGS. 3 and 4, the moldingsurface 21 f has in part a negative curvature, i.e. a concave design.The molding surface 22 f has in part a positive curvature, i.e. a convexdesign. When the injection mold 2 is closed, the cavity 23 for aliquefied thermoplastic polymer melt, which can be introduced via arunner 24, is formed between the two molding surfaces 21 f and 22 f, themolding surfaces 21 f and 22 f defining the external contours of adecorated molded part 1 that can be produced in this way.

The second decorative film 12 is placed into the first mold half 12. Thefirst decorative film is placed into the mold half 11 on the core side.The second decorative film 12 in this embodiment is provided as atransfer film and thus as a continuous material and can be fed throughthe injection-molding device 2 using a film feed unit (not shown). Thefilm feed unit can comprise a supply roll for the second decorative film12, a take-up roll for the residual film, i.e. for the optionallyremoved carrier layer 121 and residues of the decorative layer remainingon the carrier layer 121, a transport unit for the stepwise transport ofthe second decorative film 12 and a fixing device for fixing the seconddecorative film 12 on the first mold half 21.

The first decorative film 11 is provided as an inserted part, i.e. as aso-called insert, and is placed into the second mold half. For thispurpose, the first decorative film 11 is preformed in a deep-drawingprocess, in particular thermally, and stamped out. This prior thermalforming is not absolutely necessary. The subsequent edge trimming cantake place for example by stamping, milling, laser cutting or water jetcutting. The technically demanding method is suitable for continuousdecorations on decorative films 11 that have been subjected to a highdegree of three-dimensional forming. Apart from standard decorations,special degrees of gloss, a greater depth effect and abrasionresistances are possible with an additional finishing step.

The first decorative film 11 can be fixed on the molding surface 22 f bypositioning pins and/or the effect of electrostatic force and/or vacuumforce. The outlet of the runner 13 is positioned such that the polymermelt can enter between the two decorative films 11, 12 and is materiallybonded to the two decorative films 11, 12, thus forming the base element13.

FIG. 4 shows the injection-molding device 2 with injected polymer melt.The two decorative films 11, 12 are now pressed against the respectivemolding surfaces 21 f, 22 f and are materially bonded with the injectedpolymer melt. The polymer melt can be a thermoplastic polymer or athermoplastic polymer mixture, for exampleacrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC),polypropylene (PP), polymethyl methacrylate (PMMA) or a mixture ofpolycarbonate and acrylonitrile-butadiene-styrene copolymer (PC/ABS).

The above-mentioned plastics can also be used as a material for thecarrier layer 111 of the first decorative film 11. Not all materialcombinations are suitable here. They must be material combinations which

a) form an injection-molded bond with one anotherb) can be produced as plastic films that are capable of beingdeep-drawn.

Suitable combinations of the polymer melt and the carrier layer 111 arecompiled in Table 1:

Polymer melt Carrier layer Acrylonitrile-butadiene-styrene copolymer(ABS) ABS ABS/polycarbonate (PC) ABS PC/ABS ABS PC PC Polypropylene (PP)PP Polymethyl methacrylate (PMMA) PMMA

Preferred processing temperatures here are 200° C. to 300° C. Thenecessary injection pressure depends in particular on part size, partgeometry and wall thickness and can vary within a wide range.

During injection molding, in particular a tactile surface relief can bemolded into the surface of the second decorative film 12 facing awayfrom the polymer melt, in particular based on a pattern layer disposedbetween the side of the carrier film 121 facing away from the decorativeply 122 and the wall 21 f of the cavity 23.

The tactile structure is therefore formed during injection molding whenthe second decorative film 12 is capable of plastic deformation becauseof the heat and pressure of the injected polymer melt. The pattern layerin this case can be formed directly by the wall 21 f of the cavity orcan be provided by a separate insert, in particular by the carrier film121 itself.

During injection molding, furthermore, at least one core can beintroduced into the cavity 23 between the decorative films 11, 12. Thisenables hollows or recesses to be introduced into the plastic moldedpart 1, which can be used to hold functional elements, for exampleswitches, controls, backlighting devices, separate display devicesand/or touch sensors or the like. The core is preferably introduced intothe space between the decorative films 11, 12 through a cut-out in thefirst decorative film 11.

After the injection molding, a mechanical finishing can also take place,in which the plastic molded part is trimmed, milled, polished or thelike. This finishing can also take place manually. Furthermore, thefunctional parts 114 can also be mounted on the first decorative filmhere, in particular by bonding or laminating.

In FIG. 5, again multiple design variants of plastic molded parts 1 arepresented together for comparison purposes.

In the variant according to FIG. 5A, the second decorative film 12 isapplied over the entire surface and has a continuous design. The seconddecorative film 12 is dark translucent and matt here. The firstdecorative film 11 has a cut-out 115, into which for example a displaycan be inserted. In the areas where the first decorative film 11 ispresent, the desired decorative elements or the desired decorationis/are in turn introduced by means of laser, milling or stamping. Inaddition, the decorative film 11 can be positively held on the moldingsurface 22 f by means of a lug provided there and engaging in the recess115. This can increase the positional accuracy of the decorative film 11in the cavity 23, in particular in the case of large-area decorativefilms 11.

In the variant according to FIG. 5B, the second decorative film 22 alsohas a cut-out 124, which overlies the cut-out 115 of the firstdecorative film 11. The second decorative film 22 does not have acontinuous design here but comprises an individual image, whichsupplements the at least one decorative element and/or decoration of thefirst decorative film 11.

In the variant according to FIG. 5C, the second decorative film 22likewise has a cut-out 124, which overlies the cut-out 115 of the firstdecorative film 11. However, the second decorative film 22 here is againa black translucent, matt continuous design. In the base element 13itself here, a recess 131 for a display device is provided, which can beintroduced in the manner described above by using a core duringinjection molding.

1. A method for producing a plastic molded part, comprising the stepsof: a) providing a first decorative film, which at least partially hasan opaque coating; b) introducing at least one decorative element of adecoration into the first decorative film by machining using a machiningtool; c) providing a second decorative film; d) placing the decorativefilms into an injection mold having a first and second mold half, whichtogether form a cavity for molding the plastic molded part, the firstdecorative film being placed on a first wall of the cavity and thesecond decorative film on a second wall of the cavity lying opposite thefirst wall; e) back-injecting the decorative films with a polymer melt,so that the first decorative film forms a first surface and the seconddecorative film forms a second surface of the plastic molded partopposite the first surface.
 2. The method according to claim 1, whereinthe introduction of at least one decorative element of a decoration intothe first decorative film in step b) takes place by laser irradiation,milling or stamping.
 3. The method according to claim 1, wherein the atleast one decorative element is introduced into the first decorativefilm before the back injection, and before the first decorative film isplaced into the injection mold.
 4. The method according to claim 1,wherein the at least one decorative element is introduced into the firstdecorative film after the back injection.
 5. The method according toclaim 1, wherein when the decoration is introduced into the firstdecorative film using the machining tool, the opaque coating is at leastpartially removed in the area machined using the machining tool and/orthe opacity of the opaque coating is reduced in the area machined usingthe machining tool.
 6. The method according to claim 1, wherein afterthe decoration has been introduced into the first decorative film thearea machined using the machining tool and the area not machined usingthe machining tool have a difference in transparency of at least 5%. 7.The method according to claim 1, wherein the opaque coating is appliedby screen printing or intaglio printing.
 8. The method according toclaim 1, wherein the opaque coating is applied using a transfer film. 9.The method according to claim 1, wherein before the at least onedecorative element is introduced by machining using the machining tool,the opaque coating has a transparency in the wavelength range visible tohumans of less than 20%.
 10. The method according to claim 1, whereinafter the at least one decorative element has been introduced bymachining using the machining tool, in the area machined using themachining tool the opaque coating has a transparency in the wavelengthrange visible to humans of more than 75%.
 11. The method according toclaim 1, wherein the opaque coating has a layer thickness of between 5μm and 50 μm.
 12. The method according to claim 1, wherein the firstdecorative film has at least one transparent or translucent coloredcoating, a protective lacquer coating and/or an adhesive coating. 13.The method according to claim 1, wherein the at least one decorativeelement is or comprises a logo, a symbol and/or at least onealphanumeric character.
 14. The method according to claim 1, wherein atleast one further decorative element of the decoration is introducedinto the first decorative film by stamping.
 15. The method according toclaim 1, wherein the first and/or second decorative film is deep-drawnbefore being placed into the injection mold.
 16. The method according toclaim 1, wherein the first decorative film is provided in a thickness of50 to 2000 μm.
 17. The method according to claim 1, wherein the firstdecorative film has at least one ply composed of a colorless or coloredtransparent or translucent thermoplastic material.
 18. The methodaccording to claim 1, wherein the at least one decorative elementintroduced using the machining tool comprises at least one line having aline thickness of at least 0.5 mm.
 19. The method according to claim 1,wherein the second decorative film has a carrier layer, an optionalrelease layer and at least one decorative ply, wherein the decorativeply comprises at least one protective lacquer coat which is high-glossor matt and/or has been provided with a tactile structure, and whereinthe carrier layer is removed from the decorative ply after the backinjection.
 20. The method according to claim 1, wherein during the backinjection, a tactile surface relief is molded into the surface of thesecond decorative film facing away from the polymer melt, based on apattern layer which is disposed between the wall of the cavity and acarrier film of the second decorative film or the second decorativefilm.
 21. The method according to claim 1, wherein the second decorativefilm is transparent or translucent at least in some areas and has atransparency of 5% to 100%.
 22. The method according to claim 1, whereinthe decorative films are placed into the injection mold with a spacingof 0.5 mm to 10 mm.
 23. The method according to claim 1, wherein betweenthe decorative films at least one core is introduced into the injectionmold.
 24. The method according to claim 1, wherein after the backinjection, on the side of the plastic molded part formed by the firstdecorative film, at least one backlighting device and/or a touch sensor,is bonded or laminated.
 25. The method according to claim 1, wherein thefirst and/or second decorative film comprises one or more electricalfunctional layers, comprising a backlighting device or one or morecapacitive touch sensors.
 26. The method according to claim 1, whereinthe injection-molding compound has a transparency of 5% to 98% in thewavelength range visible to humans, and is formed from one of thefollowing materials: ABS (acrylonitrile-butadiene-styrene copolymer), PC(polycarbonate), ABS/PC, PC/ABS, PMMA (polymethyl methacrylate), PP(polypropylene), PA (polyamide), TPU (thermoplastic polyurethane).
 27. Aplastic molded part, manufactured by a method according to claim 1comprising a first decorative film, which at least partially has anopaque coating, into which at least one decorative element of adecoration is introduced by machining using a machining tool, andcomprising a second decorative film, wherein the first decorative filmforms a first surface and the second decorative film a second surface ofthe plastic molded part opposite the first surface.
 28. The plasticmolded part according to claim 27, wherein by the introduction of the atleast one decorative element into the first decorative film by machiningusing the machining tool, the opaque coating is at least partiallyremoved in the area machined using the machining tool and/or the opacityof the opaque coating is reduced in the area machined using themachining tool.
 29. The plastic molded part according to claim 27,wherein through the introduction of the at least one decorative elementinto the first decorative film, the area machined using the machiningtool and the area not machined using the machining tool have adifference in transparency of at least 5%.
 30. The plastic molded partaccording to claim 27, wherein the opaque coating has a transparency inthe wavelength range visible to humans of less than 20% in the area notmachined using the machining tool.
 31. The plastic molded part accordingto claim 27, wherein the opaque coating has a transparency in thewavelength range visible to humans of more than 75% in the area machinedusing the machining tool.
 32. The plastic molded part according to claim27, wherein the opaque coating a layer thickness of between 5 μm and 50μm.
 33. The plastic molded part according to claim 27, wherein the firstdecorative film has at least one further a transparent or translucentcolored coating, a protective lacquer coating and/or an adhesivecoating.
 34. The plastic molded part according to claim 27, wherein theat least one decorative element is or comprises a logo, a symbol and/orat least one alphanumeric character.
 35. The plastic molded partaccording to claim 27, wherein at least one further decorative elementof the decoration is introduced into the first decorative film bystamping.
 36. The plastic molded part according to claim 27, wherein thefirst decorative film has a thickness of 50 to 2000 μm.
 37. The plasticmolded part according to claim 27, wherein the first decorative film hasat least one ply composed of a colorless or colored transparent ortranslucent thermoplastic material.
 38. The plastic molded partaccording to claim 27, wherein the at least one decorative elementintroduced by machining using the machining tool comprises at least oneline having a line thickness of at least 0.5 mm.
 39. The plastic moldedpart according to claim 27, wherein the second decorative film comprisesat least one protective lacquer coat which is high-gloss or matt and/orhas been provided with a tactile structure and/or a tactile surfacerelief in the surface of the second decorative film facing away from thepolymer melt.
 40. The plastic molded part according to claim 27, whereinthe second decorative film is transparent or translucent at least insome areas and has a transparency of 5% to 100%.
 41. The plastic moldedpart according to claim 27, wherein the plastic molded part has a layerthickness of 0.5 mm to 10 mm.
 42. The plastic molded part according toclaim 27, wherein on the side of the plastic molded part formed by thefirst decorative film at least one backlighting device and/or a touchsensor, is bonded or laminated.
 43. The plastic molded part according toclaim 27, wherein the first and/or second decorative film has one ormore electrical functional layers, comprising a backlighting device orone or more capacitive touch sensors.